It shall be unlawful for any person to trench or excavate in any public street or alley without protecting the same at all hours with a suitable barrier, at least three feet high, constructed of one or more boards, or to place building material of any kind in a public street or alley and to allow it to remain overnight, or to make or cause any trench or excavation to be made in any public street or alley, or to cause or to create any other obstruction to a public street or alley, without stationing in a conspicuous place thereon, one or more red lights, which shall be kept burning all night. If such obstruction, excavation, or building material exceeds 50 feet in length or breadth, a red light shall be conspicuously displayed at each extremity thereof.
('74 Code, § 92.03) Penalty, see § 95.99